Axial flow pump

ABSTRACT

A MULTI-STAGE AXIAL FLOW PUMP DESIGNED TO PUMP FLUIDS WHICH MAY CONTAIN SOLID PARTICLES, WITHOUT JAMMING OR DAMAGE TO THE WORKING PARTS THEREOF. THE PUMP COMPRISES A PLURALITY OF STAGES EACH INCLUDING A STATOR ELEMENT AND A ROTOR ELEMENT CONTAINED WITHIN THE STATOR ELEMENT. THE STAGES, IN TURN, ARE LOCATED WITHIN A CYLINDRICAL HOUSING. A COMPRESSION TYPE SPRING IS LOCATED WITHIN THE HOUSING AND NORMALLY URGES THE STATOR MEMBERS AGAINST ONE ANOTHER AND AGAINST ONE END OF THE HOUSING SO THAT THEY REMAIN STATIONARY DURING NORMAL OPERATION. HOWEVER, IN THE EVENT A FOREIGN PARTICLE BECOMES LODGED BETWEEN THE ROTOR AND THE STATOR, THE STATOR IS PERMITTED TO MOVE OR SHIFT IN AXIAL POSITION SUCH THAT THE FOREIGN PARTICLE MAY PASS THERETHROUGH.

y 1972 R. v. ALBERTSON 3,676,013

AXIAL FLOW PUMP Filed Sept. 23. 1970 WATER OR FLUID INTAKE TO POWER SOURCE INVENTOR ROBERT V. ALBERTSO/V BY f/M ATTORNEY United States Patent US. Cl. 415128 6 Claims ABSTRACT OF THE DISCLOSURE A multi-stage axial flow pump designed to pump fluids which may contain solid particles, without jamming or damage to the working parts thereof. The pump comprises a plurality of stages each including a stator element and a rotor element contained within the stator element. The stages, in turn, are located within a cylindrical housing. A compression type spring is located within the housing and normally urges the stator members against one another and against one end of the housing so that they remain stationary during normal operation. However, in the event a foreign particle becomes lodged between the rotor and the stator, the stator is permitted to move or shift in axial position such that the foreign particle may pass therethrough.

BACKGROUND OF THE INVENTION The axial flow pumps of the type involved in the present invention normally includes an outer cylindrical housing having a number of stages contained therein. Each stage includes a stator element for directing and controlling the direction of the fluid flow therethrough and a rotor element which is aflixed to a shaft. -As the shaft is driven by a suitable motor, the fluid being pumped is impelled and made to pass through the stator elements. For purposes of economy, it is desirable to form the rotor and stator elements from plastic or some other inexpensive material. However, when pumps of the type described are used in an environment where they may be subjected to solid particles contained in the fluid being pumped, these particles may cause undue wear and damage to the pump unless measures are taken to accommodate the pumping of fluids containing foreign particles.

The prior art recognizes this problem and proposes solutions which are not altogether satisfactory. For example, in the Frey Pat. 3,241,493 there is disclosed an axial flow, impeller-type pump which is alleged to be capable of handling liquids carrying grit and other foreign matter. However, the solution to the problem proposed by this patent is to provide a pump that is easy to disassemble and repair when damage takes place. Rather than adopting measures to eliminate or reduce the damage caused by the pumping of grit and foreign matter, the Frey patent merely provides a means for simplified and inexpensive repair.

Similarly, the Schroeder Pat. 3,324,800 introduces a wear plate between the rotor and the pump housing or casing. If the material being pumped includes abrasive particles, according to the teachings of the Schroeder patent, the clearance between the wear plate and the housing is enlarged and it becomes necessary to periodically adjust the clearance to compensate for the wear.

The present invention can be distinguished from the foregoing prior art attempts at providing for the possibility of grit or foreign particles in the fluid being pumped. In the present invention, there is provided a means for adjusting the pressure between adjacent stator stages such that when the fluid being pumped is free of foreign particles, the stator elements remain stationary and serve their normal function. However, when foreign 3,676,013 Patented July 11, 1972 particles are present in the fluid being pumped, if a foreign particle tends to become lodged between the rotor and the stator element, the stator is free to shift axially to thereby permit the foreign particles to pass through the pump with little or no damage to the working parts thereof. In the preferred embodiment of the present invention, this is accomplished by including a coil spring within the pump casing or housing with the spring normally urging adjacent stator elements against one another and against a shoulder within the casing. Means are provided for controlling the amount of compressive force exerted by the coil spring.

It is accordingly the general object of this invention to provide an improved pump for handling a fluid which may contain solid particles.

A further object of the invention is to provide a pump wherein the stator elements are free to shift within predetermined limits in the event a foreign partcile becomes lodged between the pump rotor and the stator element.

These and other objects of the subject invention will become more fully apparent as the following description is read in light of the attached drawing wherein a partial cross-sectional elevation of a pump constructed in accordance with the invention is shown.

Referring to the drawing, the pump casing or housing is generally designated 2. Casing 2 has an inlet end 4 and an outlet end 6 and in its simplest form may comprise a cylindrical pipe or tube. The inlet end 4 of casing 2 is internally threaded at 8 so as to accept an externally threaded end cap 10. The end cap 10 is provided with an aperture 12 into which the fluid to be transported is introduced.

The pump further includesa plurality of stages indicated generally by numerals 14 and 16. While only two stages are illustrated, it should be readily apparent to those skilled in the art that additional stages may be employed to suit the particular requirements. Each stage is shown as including a cylindrical cup shaped stator element 18 having a plurality of vanes 20 for deflecting and directing the path of fluid flow therethrough. Each of the stators further has an aperture 22 passing therethrough so that a drive shaft 24 which is coaxial with the axis of the casing 2 can pass therethrough. Secured to the drive shaft 24 and located within the cup shaped stator elements is a rotor member 26. When the shaft is driven by a suitable power source (not shown) velocity is imparted to the fluid particles and these fluid particles are forced through the stator elements.

Position between adjacent stages is a flow control element 28 which, in its simplest form, comprises a flat washer or disc having an outside diameter slightly less than the diameter of the casing 2 but greater than the inside diameter of the cup-shaped stator element, such that the washer rests upon the peripheral edge of the stator element as illustrated. The flow control elements 28 have a central aperture 30 through which the fluid being pumped is directed.

In prior art pumps of the type not incorporating the present invention, the end cap 10 would be screwed down tightly against an adjacent flow control element 28 such that a substantial force is applied between adjacent stator stages and the stators are thereby rigidly locked in place. Should the fluid being pumped include foreign particles, these particles tend to become lodged between the rotor element 26 and an adjacent stator element 18. This can cause severe damage to the rotor and stator, which, as mentioned previously, are preferably formed from a suitable plastic material.

To solve this problem, the present invention provides the addition of a coil spring 32 disposed between the end cap 10 and the lowermost flow control element 28. When the end cap 10 is removed or only slightly inserted into the casing 2, little or no pressure is transferred through the coil spring element 62 to the flow control element 28. As such, adjacent stator stages 18 are not forced together nor is the lowermost stator stage forced against the abutmentor stop 34 formed on the inside of the casing. Hence, the stator elements 18 are relatively free to rotate and shift axially. This s not an altogether desirable feature in that the misalignment of the stator elements can adversely affect the desired direction of flow and efiiciency f the pump.

As the end cap is screwed further into the casing 2, an increased pressure is applied by way of the coil spring 32 to the flow control elements 28 and the stator elements 18 which they abut. When the end cap 10 is fully inserted into the casing 2, the applied pressure is such that the stator element are fixedly locked in place. However, between the two extremes, there exists a range of pressures in which the stator elements are free to shift only when a foreign particle becomes lodged between the rotor element 2'6 and a stator element 18. It is found that in practice that by allowing this slight shifting of the stator to take place, the foreign particles are freed and allowed to pass through the pump. As a result, very little damage is done to the internal parts of the pump.

Thus, it can be seen that the present invention provides an improvement for prior art pumps to allow coarse objects and sedimentary material such as sand, gravel, etc.-

to pass through the rotors and stators with a minimum of damage. This is accomplished by adjusting the pressure applied to the stators to allow them to rotate or shift slightly when subjected to forces caused by an object trapped between the rotors and stators. Thus, when an object does become lodged between the rotor and the stator, the stator can shift its position slightly by moving about its longitudinal axis. This slight motion permits the lodged object to align itself with an opening in the stator and pass through it into the next stage.

While an embodiment of the invention has been described, it is appreciated that various changes and modifications may be made without departing from the invention. It is desired to cover all such changes and variations as would be apparent to one skilled in the art, and that come within the scope of the appended claims.

It is claimed and desired to secure by Letters Patent:

1. An improved axial flow pump capable of pumping fluids containing solid particles, said pump being of the type including a cylindrical housing having an inlet port and an outlet port, at least one cylindrical cup-shaped stator member contained within said housing, a drive shaft mounted coaxially Within said housing and a rotor member mounted on said shaft and adapted to rotate within said cup-shaped stator, the improvement comprising:

4 means for yieldably holding said stator member in rotatable contact with said housing whereby a foreign particle that becomes lodged between the rotor and stator will free itself and pass downstream through the pump.

2. Apparatus as in claim 1 wherein said last named means comprises:

(a) a compression spring located within said housing and contacting said stator member, and

(b) means for adjustably compressing said spring.

3. Apparatus as in claim 2 and further including a flat washer disposed between said spring and said stator member.

4. Apparatus as in claim 2 wherein said last named means comprises a threaded cap member which is adapted to be screwed intothe inlet end of said housing.

5. An improved multi-stage axial flow pump of the type having a cylindrical housing having an inlet end and an outlet end and wherein each stage includes a cylindrical cup-shaped stator located within said housing member and a rotor member adapted to fit within said cup-shaped portion of said stator member and adapted to be driven by a drive shaft passing through a central aperture in said stator member, and wherein the stages are separated by a flat washer member disposed between adjacent stator members, the improvement comprising:

means for yieldably urging said stator members against said flat washers such that said stator members are normally stationary within said housing yet axially rotatable in the event a solid particle lodges between a rotor member and an associated stator member to free the lodged particle for movement downstream through the pump.

6. Apparatus as in claim 5 wherein said last named means comprises a coil spring contained within said housing having one end abutting said flat Washer and the other end abutting an axially movable member.

References Cited UNITED STATES PATENTS 640,345 1/ 1900 Wilberforce 415-197 2,670,686 3/1954- Bergh 417424 3,158,295 Ill/1964 McConaghy 415199 R 3,490,685 Y 1/1970 Ferri 415197 2,347,386 4/ 1944 Adams 415-214 FOREIGN PATENTS 491,167 2/1954 Italy 415200 HENRY F. RADUAZO, Primary Examiner U.S. Cl. X.R. 415-501, 199, 219 

